Pyrrole methine and tri-methine cyanine backing dyes



Patented Jan. 6, 1942 PYRROLE METHINE AND TRIY-METHINE CYANINE BACKING DYES Leslie G. S. Brooker and Robert H. Sprague,

Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application February 7, 1940, Serial No. 317,127 -In Great Britain February 17, 1939 6 Claims. (Cl. 95-8) This invention relates to. improvements in photographic elements and more particularly to backing or anti-halation dyes for use in photographic elements. I

The use of overcoating or backing layers containing light absorptive dyes for use in photographic films or plates is well known. These light screening substances are often required in overcoatings upon photographic elements to protect the light sensitive emulsion from the action of light which it is not desired to record or in backing layers forming so -called anti-halation layers on either side of a transparent support carrying the light-sensitive emulsion or emulsions.

In photographic elements it is generally necessary to employ light-screening substances which can readily be rendered ineffective, that is decolorized or destroyed and removed prior to, during, or after photographic processing. For many purposes it is particularly convenient to employ light-screening substances which are rendered inefiective by one of the photographic baths em ployed in processing the element after exposure, that is photographic developing or fixing bath or a silver oxidizing (including silver removing) bath. For example, in an element which is to be processed by reversal it is often convenient to employ a light-absorbing substance which is rendered ineifective by the developer employed to develop the latent image or images to silver, since exposure to light of the residual lightsensitive emulsion or emulsions may thereby be facilitated. This is particularly true in the case of color photography where several difierentially sensitized emulsions composed, for example, of silver halide, such as silver bromide, dispersed in gelatin, collodion, or other colloid are coated on one or both sides of a support. It may be desirable in such cases to expose the photographic element from the rear side during procrequirements of light screening substances for This class consists of methine and tri-methine cyanine dyes use in photographic elements.

derived from pyrrole or vfrom its substituted derivatives.

Such dyes may have a pyrrole nucleus, substituted or unsubstituted, the nitrogen atom of which may also form a part of the pyridine nucleus, linked through an'intermediate polymethine chain so that there is a chain of an odd number 01 carbon atoms having conjugated double linkages between the nitrogen atoms.

In the drawing the figures are enlarged sectional views of photographic elements showing overcoating or anti-halation layers according to our invention.

The compounds which we propose to use as screening dyes have the following general formula:

where i Z and Z'=the non-metallic atoms necessary to complete a pyrrole nucleus, and may bethe same or different.

R and R=hydrogen, alkyl, or a chemical bond Example 1 C H=C lcn Hexyl Hexyl Bis (2 hex'yl 1 pyrrocoline methine cyanine perchlorate.

3.0 g. (2 mols) 2-hexylpyrrocoline, 6.7 g. (1 mol+500%) ethylorthoformate and 25 cc. glacial acetic acid were stirred mechanically at room temperature for 5 minutes. Blue coloration at once. -2.3 g. (1 mol+%) Na I added and stirring continued for 25 minutes. Diluted to 100 cc. with ether and chilled. No crystals separated. 1.8 g. (1 mol+100%) 'NaClOr in 25 cc.

- tion at once.

, utes longer.

Bis (2 methyl 1 pyrrocoline) methine-cyanine iodide.

Example 2 2.6 g. (2 mols) 2-methyl pyrrocoline, 3.0 g. (1 mol+100%) ethyl orthoformate and 20 cc. glacial acetic acid were stirred mechanically with heating on steam pot for 1 minute. Blue coloration at once. Steam shut oflf and stirring continued 5 minutes. 3.0 g. (1 mol+100%) sodium iodide added and mixture stirred 2 minutes longer. Chilled, filtered, washed with acetone and water and dried. Yield of blue-green crystals. 3.55 g.,

89%. After recrystallization from MeOH (35 cc., 1 g.) the product was obtained as green crystals melting with decomposition at 232-233". Yield 1.5 g., 37%. MeOH solution blue.

Bis- (2-phenyl-1-pyrrocoline) methine-cyanine iodide.

3.86 g. (2 mols) 2-phenylpyrrocoline, 3.0 g. (1 mol+100%) ethylorthoformate and cc. glacial acetic acid were stirred mechanically with heating on steam pot for 1 minute. Blue colora- Steam shut 011 and stirring continued 5 minutes. 3.0 g. (1 mol+100%) sodium iodide added and mixture stirred 2 minutes longer. Green crystals separated from the hot solution; chilled, filtered, washed with acetone and water and dried. Yield of violet crystals 4.0 g., 76%. After recrystallization from Me0H., (33 cc., 1 g.) the dye was obtained as bronze crystals melting with decomposition at 165-166. Yield 2.2 g., 42%. MeOH solution blue.

} Bis- (2,3-dimethyl-l-pyrrocoline) -methine-cyanine iodide.

2.9 g. (2 mols) 2,3-dimethylpyrrocoline, 9.0 g. (1 mol+500%) ethylorthoformate and cc. glacial acetic acid were stirred mechanically at room 3.0 g. (1 mol+100%) NaI-were added and the mixture stirred 10 min- Green crystals separated. Chilled, filtered, washed with acetone and water and dried. Yield 3.6 g., 84%, After recrystallization from MeOH, (27 cc., 1 g.). the dye washbtained as green crystals with bright green reflex melting with decomposition at 269-271. Yield 3.1 g., 72%. Solution blue in MeOH.

Example 5 CELN CHI CHI\\NJCHI my Hep a1 Bis- (1-hepty1-2,5-dimethyl-3-pyrrole) methinecyanine percholorate.

2.2 g. (1 mol) 1-heptyl-2,5-dimethyl-3-pyrrolealdehyde, 1.9 g. (1 mol) 1-heptyl-2,5-dimethylpyrrole, 1.1 g. (1 mol) 35% hydrochloric acid and 15 cc. absolute CzHsOH were refluxed 30 minutes. Orange coloration. A solution of 2.4 g. (1 mol+%) sodium perchlorate in 15 cc. CHaOH was added and the mixture cooled. Dlluted to 200 cc. with ether and chilled. Flltered, washed with ether and water and dried. Yield of orange crystals 2.2 g., 44%. After recrystallization from absolute CaI-IsOH, (11 cc., 1 g.) the dye was obtained as bright orange flakes melting with decomposition at -151". Yield 1.8 g., 36%. MeOH solution yellow.

Example 6 Lauryl ether and water and dried. Yield of orange crystals 3.8 g., 59%. After recrystallization from absolute C2H5OH, (8 cc., 1 g.) the dye was obtained as bright orange crystals melting with decomposition at 158-160". Yield 3.6 g., 56%. MeOH solution yellow.

' Example 7 L o--c11 CHa=JJCHs CHrLNHCHa \I Lauryl (1 Lauryl 2,5 dimethyl 3 pyrrole)-(2,3- dimethyl-l-pyrrocoline) methine-cyanine iodide.

2.0 g. (1 mol) 2,3-dimethylpyrrocoline, 4.0 g. (1 mol) 1-lauryl-2,5-dimethyl-3-pyrrolealdehyde, 1.5 g. (1 mol) 35% hydrochloric acid and 15 cc. absolute CzH5OH- were refluxed 5 minutes. Reddishorange coloration. A solution of 5 g. (1 mol+ 150%) No.1 in 15 cc..CHsOH was added and the mixture boiled 1 minute with stirring. Cooled, diluted to 700 cc. with ether and chilled. Dye filtered ofl, washed with ether and water and dried. Yield of redmstals 5.4 g., 72%. After recrystallization from absolute C2H5OH, (11 cc., 1 g.) the dye was obtained asred. crystals .lutionblui-shiedinMeOH.

melting at 144-145 with decomposition. Yield 4.5 g.,- 60%. MeOH solution pinkish orange.

Example 8 Lauryl (l Lauryl -2,5 dimethyl 3 pyrrolei-(2- 'methyl-l-pyrrocoline) methine-cyanine iodide.

2.6 g. (1 mol.) 2-methylpyrrocoline, 5.8 grams (1 mol.) l-lauryl- 2,5-dimethyl-3-pyrrolealdehyde, 6.0 g. (1 mo 1+100%) sodium iodide, 2.2 g.

(1 mol.) 35% hydrochloric acid and 25cc. absolute C2H5OH were refluxed 5 minutes. The red mixture was chilled, the dye which separated was filtered oil, washed with water and acetone and dried. Yield of red crystals, 7.9 g., 75%. After recrystallization from CHaOH, cc. 1 g.) the product was obtained as felted red crystals melting with decomposition at '146-148. Yield 4.9 g., 46%, Solution pink in CHaOH. Bleached by developer. No' sensitizing action. No diffusion when coated in multi-layer gelatine coating.

Example- 9 Bis-(2,3-dimethyl-l-pyrrocoline) 'mmetmnecyanine bromide. p

2.9 g.'(2 mols.) 2,3-dimethy1pyrrocoline, 2.6 g.

(1 mol.) p-anilinoacrolein anil hydrochloride, 2.0

g. (1 mol.+100%) sodium bromide and 25 cc. acetic anhydride were refluxed 5 minutes. The blue reaction mixture acetone and chilled to 0 C. The dye was filtered off, washed with acetone and water and dried. Yield of green solid 2.4 g., 83%.

obtained as bright blue-green crystals melting with decomposition at 2'73-274. Yield 2.7 g., 66%. MeOH solution blue.

Example 10 Bis-(1,2-dimethyl-3-indole). trimethinecyanine iodide.

2.9 g. (2 mols.)' 1,2-dimethylindoie, 2.6g. (1 mol.) p-anilinoacrolein anil hydrochloride, 3.0 g. (1 mol.+100%) sodium iodide and cc. acetic anhydride were refluxed 5 minutes. The purple solution was chilled to 0 C., the dye filtered on,

washed withacetone and water and dried. Yield of dull blue crystals 2.1 g., 46%. ter crystallization from MeOH, (10'75 ccT/g.) the dye was obtained as shiny blue crystals melting with decomposition at 237 2'39. Yield 1.3 g., 29%. 80-

was diluted with cc.

After crystallization from MeOH (165 00/3.) the product was m Example 1 melting with decomposition-at 165-166. Yield 1.2 grams, 17%. MeOH solution bluish-red.

For the preparation of overcoating layers, filter layers and anti-halation layers according to our invention, from 50 mg. to mg. of dye are dissolved in from 2 to 5 cc. of .a water miscible solvent. Methanol and acetone are suitable for this purpose but pyridine and Cellosolve may also be used. The solution is then added to about 25 cc. of a. 5% gelatin solution at 40 C. and the mixture coated on a support. If the dye is too insoluble as the iodide salt,it may conveniently be convertedv into the chloride using'cresol as a solvent for the conversion.

In the accompanying drawing the various figures are, enlarged sectional views of photographic' elements having overcoating layers and antihalation layers made according to our invention. As shown in Fig. 1, a support of 10 of any suitable material such as cellulose nitrate or cellulose acetate, resinous material, or opaque material such as paper is coated with an emulsion layer- II and an overcoating layer l2 containing a bismethine-cyanine dye containing a pyrrole nucleus according to our invention.

Fig. 2 represents a film having an anti-halation bis-methine cyanine pyrrole layer containing a dye according to our invention. As shown therein, the support 10 contains an emulsion layer H on one side a d an anti-halation layer 18 contaming-the bis-methine cyanine dye on the opposite side.

Our invention is not limited to the examples included in the present specification but any compounds coming within the scope of the inin gelatin,

7 inaor'other suitable colloid or they may be disvention may be used. T'I'he dye may be dispersed collodion, gum arabic, synthetic restine-silver halide emulsions and may becoated in any suitable manner. It is 'to be understood persed in photographic emulsions such as gelathat our invention is limited only by the scope oithe appended claims.

We claim: 1

1. A photographic element comprising a sensitive layer and alight-absorbing layer containing a dye having the following formula:

in' which Z'and Z'=the non-metallic atoms necessary tocomplete a pyrrol' nucleus, and may be the same or. diflerent: R and R'=hyd rogen,

alkyl, or a' chemical'bond in a pyridine ring;-

smegma ing a filter layer containing bis- (Z-hexyl-l-pyrrocoline) methine cyanine perchlorate.

5. A sensitive photographic element comprising a filter layer containing bis- (Z-methyl-lpyrrocoline) metalnne cyanine iodide.

6. A sensitive photographic element compris ing a. filter layer containing 1215- (2-phenyl-1 pyrrocoline) methine cyanine iodide.

LESLIE G. s. BROOKER. ROBERT H. SPRAGUE. 

